A key chain rechargeable device which is recharged when a key is inserted into a matching lock. In accordance with one embodiment, the key includes two electrical contacts or is separated into two electrically isolated portions. The two electrical contacts or portions of the key contact mating contacts in the matching lock only when the key is inserted therein. In another embodiment, inductive coupling is used when the key chain rechargeable device is proximate to a matching lock of a key associated therewith. A charging circuit may be integrated in the key chain rechargeable device or in the external device associated with the lock. The key chain rechargeable device may be, e.g., a wireless device such as a BLUETOOTH™ network device, pager, a security alarm enable/disable device, garage door opener, or a keyless entry remote. In a preferred embodiment, the key relates to a vehicle ignition key, and the key chain rechargeable device is recharged during operation of a vehicle.